ContainerOrderFocusTraversalPolicy.java revision 2362
0N/A * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 0N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 0N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 0N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 0N/A * or visit www.oracle.com if you need additional information or have any 0N/A * A FocusTraversalPolicy that determines traversal order based on the order 0N/A * of child Components in a Container. From a particular focus cycle root, the 0N/A * policy makes a pre-order traversal of the Component hierarchy, and traverses 0N/A * a Container's children according to the ordering of the array returned by 0N/A * <code>Container.getComponents()</code>. Portions of the hierarchy that are 0N/A * not visible and displayable will not be searched. 0N/A * By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus 0N/A * down-cycle. That is, during normal forward focus traversal, the Component 0N/A * traversed after a focus cycle root will be the focus-cycle-root's default 0N/A * Component to focus. This behavior can be disabled using the 0N/A * <code>setImplicitDownCycleTraversal</code> method. 0N/A * By default, methods of this class with return a Component only if it is 0N/A * visible, displayable, enabled, and focusable. Subclasses can modify this * behavior by overriding the <code>accept</code> method. * This policy takes into account <a * if a focus traversal policy provider is encountered, its focus traversal * policy is used to perform the search operation. * @author David Mendenhall * @see Container#getComponents * JDK 1.4 serialVersionUID * Used by getComponentAfter and getComponentBefore for efficiency. In * order to maintain compliance with the specification of * FocusTraversalPolicy, if traversal wraps, we should invoke * getFirstComponent or getLastComponent. These methods may be overriden in * subclasses to behave in a non-generic way. However, in the generic case, * these methods will simply return the first or last Components of the * sorted list, respectively. Since getComponentAfter and * getComponentBefore have already built the list before determining * that they need to invoke getFirstComponent or getLastComponent, the * list should be reused if possible. * We suppose to use getFocusTraversalCycle & getComponentIndex methods in order * to divide the policy into two parts: * 1) Making the focus traversal cycle. * 2) Traversing the cycle. * The 1st point assumes producing a list of components representing the focus * traversal cycle. The two methods mentioned above should implement this logic. * The 2nd point assumes implementing the common concepts of operating on the * component. These concepts are described in the AWT Focus Spec and they are * applied to the FocusTraversalPolicy in general. * Thus, a descendant of this policy may wish to not reimplement the logic of * the 2nd point but just override the implementation of the 1st one. * A striking example of such a descendant is the javax.swing.SortingFocusTraversalPolicy. * Checks if a new focus cycle takes place and returns a Component to traverse focus to. * @param comp a possible focus cycle root or policy provider * @param traversalDirection the direction of the traversal * @return a Component to traverse focus to if {@code comp} is a root or provider * and implicit down-cycle is set, otherwise {@code null} " in the focus cycle root " +
cont);
* Returns the Component that should receive the focus after aComponent. * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider. * By default, ContainerOrderFocusTraversalPolicy implicitly transfers * focus down-cycle. That is, during normal forward focus traversal, the * Component traversed after a focus cycle root will be the focus-cycle- * root's default Component to focus. This behavior can be disabled using * the <code>setImplicitDownCycleTraversal</code> method. * traversal policy provider</a>, the focus is always transferred down-cycle. * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider * @param aComponent a (possibly indirect) child of aContainer, or * @return the Component that should receive the focus after aComponent, or * null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is not a focus cycle * root of aComponent or focus traversal policy provider, or if either aContainer or // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root. // If it's the case just go down cycle (if it's set to "implicit"). // See if the component is inside of policy provider. // FTP knows how to find component after the given. We don't. // Null result means that we overstepped the limit of the FTP's cycle. // In that case we must quit the cycle, otherwise return the component found. * Returns the Component that should receive the focus before aComponent. * aContainer must be a focus cycle root of aComponent or a <a * @param aContainer a focus cycle root of aComponent or focus traversal policy provider * @param aComponent a (possibly indirect) child of aContainer, or * @return the Component that should receive the focus before aComponent, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is not a focus cycle * root of aComponent or focus traversal policy provider, or if either aContainer or // See if the component is inside of policy provider. // FTP knows how to find component after the given. We don't. // Null result means that we overstepped the limit of the FTP's cycle. // In that case we must quit the cycle, otherwise return the component found. // If the provider is traversable it's returned. * Returns the first Component in the traversal cycle. This method is used * to determine the next Component to focus when traversal wraps in the * @param aContainer the focus cycle root or focus traversal policy provider whose first * Component is to be returned * @return the first Component in the traversal cycle of aContainer, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is null * Returns the last Component in the traversal cycle. This method is used * to determine the next Component to focus when traversal wraps in the * @param aContainer the focus cycle root or focus traversal policy provider whose last * Component is to be returned * @return the last Component in the traversal cycle of aContainer, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is null * Returns the default Component to focus. This Component will be the first * to receive focus when traversing down into a new focus traversal cycle * rooted at aContainer. The default implementation of this method * returns the same Component as <code>getFirstComponent</code>. * @param aContainer the focus cycle root or focus traversal policy provider whose default * Component is to be returned * @return the default Component in the traversal cycle of aContainer, * or null if no suitable Component can be found * @see #getFirstComponent * @throws IllegalArgumentException if aContainer is null * Sets whether this ContainerOrderFocusTraversalPolicy transfers focus * down-cycle implicitly. If <code>true</code>, during normal forward focus * traversal, the Component traversed after a focus cycle root will be the * focus-cycle-root's default Component to focus. If <code>false</code>, * the next Component in the focus traversal cycle rooted at the specified * focus cycle root will be traversed instead. The default value for this * property is <code>true</code>. * @param implicitDownCycleTraversal whether this * ContainerOrderFocusTraversalPolicy transfers focus down-cycle * @see #getImplicitDownCycleTraversal * @see #getFirstComponent * Returns whether this ContainerOrderFocusTraversalPolicy transfers focus * down-cycle implicitly. If <code>true</code>, during normal forward focus * traversal, the Component traversed after a focus cycle root will be the * focus-cycle-root's default Component to focus. If <code>false</code>, * the next Component in the focus traversal cycle rooted at the specified * focus cycle root will be traversed instead. * @return whether this ContainerOrderFocusTraversalPolicy transfers focus * @see #setImplicitDownCycleTraversal * @see #getFirstComponent * Determines whether a Component is an acceptable choice as the new * focus owner. By default, this method will accept a Component if and * only if it is visible, displayable, enabled, and focusable. * @param aComponent the Component whose fitness as a focus owner is to * @return <code>true</code> if aComponent is visible, displayable, * enabled, and focusable; <code>false</code> otherwise // Verify that the Component is recursively enabled. Disabling a // heavyweight Container disables its children, whereas disabling // a lightweight Container does not.